How to use actuator_control topic in MAVROS

ROS / MAVROS / MicroDDS
1

Hello,

I want to control each of the rotors directly in Offboard mode and thought I can do this using actuator_control topic. However, I am having difficulties in how to use this topic. My 2 main questions are:

  1. What values I have to use for “group mix” and “control” parameters

Screenshot from 2021-07-28 14-18-22
Screenshot from 2021-07-28 14-18-22732×468 43.7 KB

I think I have to use value 3 for the mixer group which is PX4_MIX_MANUAL_PASSTHROUGH, but I don’t know the parameters for “control” to control each actuators.

  1. The description of this topic says “Sends actuator commands to FCU”. Does this imply that I have to use additional Pixhawk connection to use this topic, unlike the usual setpoint topics?

Thanks,
Kangmin